1. Field of the Invention
The invention relates generally to pressure and temperature relief valve arrangements, and, more particularly, to pressure and temperature relief valve arrangements for restricting coolant flow through a water cooled internal combustion engine. The invention also relates to a pressure responsive diaphragm valve for use in the valve arrangement.
2. Reference to Prior Art
Numerous valve arrangements have been employed for use in the cooling systems of internal combustion engines. Conventional temperature and pressure relief valve assemblies which are used in engine cooling systems and which restrict coolant flow through the engine include two separate and independent valve members which seat on separate valve seats. One of the valve members is generally temperature responsive, and the other of the valve members is generally operable in response to high fluid pressure in the cooling system caused by high engine speeds and the resulting high coolant flow rate. The temperature responsive valve is commonly actuated by a thermostat comprising a body enclosing a thermally responsive material, and a rod and piston arrangement which moves in response to expansion or contraction of the thermally responsive material. The pressure setting at which the pressure responsive valve unseats is commonly determined by compressing a biasing spring for the valve to a desired degree. The thermally responsive valve member is also commonly biased into a seated position by a spring.
Conventional valve arrangements commonly employ valves and valve seats made of metal. The use of metal valves and valve seats can lead to corrosion of the valve components.
Attention is directed to the following United States Patents:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 1,972,170 Spencer September 4, 1934 2,497,201 Banner February 4, 1950 2,570,432 Dillon October 9, 1951 2,740,586 Chaniot April 3, 1956 2,785,861 Kimm et al. March 19, 1957 2,810,527 Work October 22, 1957 3,498,537 Backman Wong March 3, 1970 3,512,710 Resta May 19, 1970 3,700,166 Foults October 24, 1972 3,724,753 Thornton April 3, 1973 4,078,722 Luckenbill March 14, 1978 4,344,564 Magnuson August 17, 1982 ______________________________________